During the petrochemical processing of chlorinated hydrocarbons, they are commonly heated to temperatures of 38.degree. C. to 815.degree. C. This processing typically comprises production and purification processes such as distillation and fractionation. Ethylene dichloride (EDC) is most commonly used in the production of vinyl chloride monomer (VCM).
Ethylene dichloride, also known as 1,2-dichlorethane, is produced from ethylene by two different processes: the direct chlorination of ethylene and the oxychlorination of ethylene. Direct chlorination uses ferric chloride, tetrachloroferrate salts, aluminum chloride or cupric chloride as catalysts.
Oxychlorination of ethylene is typically incorporated into an integrated vinyl chloride plant in which hydrogen chloride, recovered from the dehydrochlorination or cracking of ethylene dichloride to vinyl chloride, is recycled to an oxychlorination unit. The process further employs an oxygen-containing gas such as air or oxygen.
As a result of these processes, ethylene dichloride will often contain impurities such as iron complexes due to the catalyst and corrosion of process equipment and other organic chloride compounds and tars. Ethylene dichloride must be purified prior to its cracking to produce vinyl chloride monomer and the impurities formed during the production of ethylene chloride must be removed. The most common impurities in ethylene chloride include but are not limited to butadiene, chloroprene, vinylidene chloride, chlorinated methane, acetylene, and ethylene. This is typically accomplished with washing and distillation steps. However, after some usage the distillation and purification units begin to foul due to the accumulation of impurities. The deposition of these impurities, often polymeric in nature, result in less efficient economies of production as well as shut-down to clean the fouled unit.